Internesting Period and Clutch Frequency of the Endangered Loggerhead Turtle Population of Cabo Verde

Abstract

Knowledge about the reproductive success of sea turtles is essential for their conservation. These nest preferentially on the beaches where they were born and may nest more than once during each nesting season, with a variable number of nests per female. Several factors can lead to variations in reproductive output. This study estimated the clutch frequency and internesting period of the threatened subpopulation of the loggerhead turtle (Caretta caretta) from the island of Boa Vista, Cabo Verde. This archipelago hosts the second-largest (or perhaps largest) population of C. caretta globally, with Boa Vista being the most important nesting island. Female distinctions were made on their previous experience (neophytes and remigrants) and their body size. Data were collected between 2013 and 2020 through marking and recapture, on João Barrosa beach, in the Reserva Natural das Tartarugas. In years with more females nesting on beaches, a smaller percentage of nests are studied because of the difficulty in reporting them all. As such, only the first 25% of the nests were analysed. Minimum clutch frequency ranged between 3.8 and 4.1. Remigrants had a larger body size and higher clutch frequency than neophytes, without differences in the internesting period. This study also showed differences between neophyte and remigrant females, specifically only in their measured clutch frequency. However, neophytes likely switch between nesting grounds more often, evading monitoring, and highlighting their potential to move to other islands or to breed out of the main season. These findings enhance our understanding of reproductive strategies, enabling the application of distinct conservation strategies tailored to each group. Satellite telemetry could address study limitations regarding clutch frequency values and provide a better understanding of nesting patterns and the impact of environmental factors on reproduction. This could improve conservation strategies by identifying critical habitats and guiding targeted protective measures, supporting population recovery.